Recent works in micro-scale magnetic actuation have enabled the creation of micron-scale permanent magnets for the application of forces and torques via externally-generated magnetic fields for micro-fluidic pumps and mixers, mobile micro-robots and other micro-devices. The ability to remotely and repeatedly turn “on” and “off” magnetic micro devices is an unsolved problem in the field, which could be used, for example to address devices that cannot directly contacted, or to individually address multiple devices which share the same workspace in enclosed environments, such as in micro-fluidic channels in lab-on-a-chip devices or in medical devices such as capsule endoscopes where remote actuation of numerous actuators is desired.